Definition of "theine" [the•ine]

• Caffeine when present in tea (noun)

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• "The leaves yield the same bitter principle called theine, which is found in the leaf of the Chinese tea-plant, the coffee berry, &c."
• "The active principle of tea is called theine; that of coffee, caffeine, and of cocoa, theobromine."
• "The chemical principle of tea, namely theine, was subsequently tried and produced no effect."